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Precisely Controlled Microsphere Design via Visible‐Light Cross‐Linking of Functional Prepolymers
摘要： A new strategy for particle synthesis is enabled by utilizing modern synthetic, polymer, and photochemical techniques to facilitate the synthesis of highly narrow–disperse multifunctional microspheres from visible-light induced crosslinking of prepolymers in both a single and dual polymer system. The approach requires no stabilizers, bases, or initiators, and proceeds at ambient temperature to yield microspheres with a tunable size range (0.25–5 μm) in less than 4 h, depending largely on solvent composition, but also polymer concentration (2–10 mg mL?1), ratio, and irradiation intensity (3–20 W). Critically, the visible-light induced dimerization reaction exploited herein enables simple functional particle syntheses via a single polymer system. Underpinned by an in-depth kinetic analysis of the particle formation as well as a detailed small molecule study, the mechanism for particle formation is also elucidated. Importantly, inherent advantages of the system are exploited for surface functionalization of residual acrylate and hydroxyl groups (generating inherently fluorescent particles).
关键词： polymer chemistry,photochemistry,materials chemistry,precipitation polymerization,particle synthesis
更新于2025-09-11 14:15:04
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Finely Controlled Circularly Polarized Luminescence of a Mechano-Responsive Supramolecular Polymer
摘要： We report on finely controlled circularly polarized luminescence (CPL) supramolecular polymerization based on a tetraphenylethene core with four L- or D-alanine branch side chains (L-1 and D-1) in the solution state resulting from the tuning of mechanical stimulus. Weak, green emissions of L-1 and D-1 in tetrahydrofuran (THF) were converted to strong blue emissions by tuning the mechanical stimulus. The strong blue emissions were caused by an aggregation-induced emission (AIE) effect during the formation of a supramolecular polymer. Lag time in the supramolecular polymerization was drastically reduced by the mechanical stimulus, which was indicative of the acceleration of the supramolecular polymerization. Interestingly, a significant enhancement of circular dichroism (CD) and CPL signals of the L-1 and D-1 was observed by tuning the rotational speed of the mechanical stimulus, which implies that the chiral supramolecular polymerization was accelerated by the mechanical stimulus. These results imply that the CPL signals were tuned by the strength of the external mechanical stimulus.
关键词： Helicity,AIE Effect,Mechano-Responsive Material,Circularly Polarized Luminescence,Supramolecular Polymerization
更新于2025-09-11 14:15:04
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Precise Synthesis of Ultra-High-Molecular-Weight Fluoropolymers Enabled by Chain-Transfer Agent Differentiation under Visible-Light Irradiation
摘要： A photo-mediated reversible-deactivation radical polymerization has been developed based on a novel chain-transfer agent (CTAs) differentiation mechanism, enabling the precise preparation of fluoropolymers with ultra-high molecular weights, narrow molecular weight distributions and excellent chain-end fidelity at complete conversions. Moreover, this synthetic approach is efficient, scalable, temporally controllable and compatible to a variety of monomers and CTAs.
关键词： block copolymers,photochemistry,polymerization,synthetic methods,fluorine
更新于2025-09-11 14:15:04
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<i>ipso</i> -Arylative Ring-Opening Polymerization as a Route to Electron-Deficient Conjugated Polymers
摘要： ipso-Arylative ring-opening polymerization of 2-bromo-8-aryl-8H-indeno[2,1-b]thiophen-8-ol monomers proceeds to Mn up to 9 kg mol(cid:2)1 with conversion of the monomer diarylcarbinol groups to pendent conjugated aroylphenyl side chains (2-benzoylphenyl or 2-(4-hexylbenzoyl)phenyl), which influence the optical and electronic properties of the resulting polythiophenes. Poly(3-(2-(4-hexylbenzoyl)phenyl)thiophene) was found to have lower frontier orbital energy levels (HOMO/LUMO = (cid:2)5.9/(cid:2)4.0 eV) than poly(3-hexylthiophene) owing to the electron-withdrawing ability of the aryl ketone side chains. The electron mobility (ca. 2 (cid:2) 10(cid:2)3 cm2 V(cid:2)1 s(cid:2)1) for poly(3-(2-(4-hexylbenzoyl)phenyl)thiophene) was found to be significantly higher than the hole mobility (ca. 8 (cid:2) 10(cid:2)6 cm2 V(cid:2)1 s(cid:2)1), which suggests such polymers are candidates for n-type organic semiconductors. Density functional theory calculations suggest that backbone distortion resulting from side-chain steric interactions could be a key factor influencing charge mobilities.
关键词： ipso-arylative polymerization,ring-opening polymerization,conducting materials,cross-coupling,palladium
更新于2025-09-10 09:29:36
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Visible light 3D printing with epoxidized vegetable oils
摘要： Stereolithography is a 3D printing technique in which a liquid monomer is photopolymerized to produce a solid object. The most widely used materials usually belong to the family of acrylate monomers, and photopolymerization occurs through a radical pathway. Photoinitiators can absorb UV or (less often) visible light, producing radicals for direct decomposition or hydrogen abstraction. Due to the toxicity of acrylates, vegetable oil-derived monomers were used in this study. In fact, vegetable oils contain unsaturations, and thus, they can be exploited as monomers. In particular, linseed oil, tung oil or edible oils (soybean, sunflower or corn) could be good candidates as raw materials. Unfortunately, the photoinduced radical polymerization of these oils either does not occur or is too slow for 3D printing applications. For this reason, the oils were modified as epoxides. Epoxides are monomers that are more reactive than natural oils, and they can be polymerized via a cationic mechanism. The aim of this work was to exploit visible light generated by a common digital projector (like those used in classrooms) as a light source. Since the tested photoacid generators working under visible light are ineffective for the polymerization of epoxidized oils, a multi-component photo-initiating mixture was used.
关键词： Green resins,Photoinduced cationic polymerization,Ring opening polymerization,Visible light stereolithography,Vegetable oil epoxides
更新于2025-09-10 09:29:36
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Two-Photon Polymerization as a Tool for Studying 3D Printed Topography-Induced Stem Cell Fate
摘要： Geometric topographies are known to influence cellular differentiation toward specific phenotypes, but to date the range of features and type of substrates that can be easily fabricated to study these interactions is somewhat limited. In this study, an emerging technology, two-photon polymerization, is used to print topological patterns with varying feature-size and thereby study their effect on cellular differentiation. This technique offers rapid manufacturing of topographical surfaces with good feature resolution for shapes smaller than 3 μm. Human-induced pluripotent stem cells, when attached to these substrates or a non-patterned control for 1 week, express an array of genetic markers that suggest their differentiation toward a heterogeneous population of multipotent progenitors from all three germ layers. Compared to the topographically smooth control, small features (1.6 μm) encourage differentiation toward ectoderm while large features (8 μm) inhibit self-renewal. This study demonstrates the potential of using two-photon polymerization to study and control stem cell fate as a function of substrate interactions. The ability to tailor and strategically design biomaterials in this way can enable more precise and efficient generation or maintenance of desired phenotypes in vitro and in vivo.
关键词： induced pluripotent stem cells,differentiation,substrate topography,3D printing,two-photon polymerization
更新于2025-09-10 09:29:36
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Aryl–Aryl Coupling on Semiconductor Surfaces
摘要： Bottom-up strategies in nanotechnology offer unprecedented precision in fabrication of functional structures and devices. Soon after the advent of scanning probe microscopies in the 1980s, it was demonstrated that on-surface nanoobjects may be constructed at ultimate level of control—one atom at a time. Later on, it was shown that even a chemical reaction between two molecular entities is manageable in a stepwise fashion—all steps of a chemical reaction may be induced with scanning tip at will. The limits of precision have been reached. If one considers practical implementations, however, a major obstacle of tip-induced processes appears to be their tediousness. Alternative, fast, yet, precise routes to nanostructure formation are sought. In such a context non-locally induced procedures seem to be especially rewarding. There are, still, at least two expectations with regard to nonlocally induced chemical reactions. First, there is a need for a kind-of-trigger that will allow for a controlled activation of a given procedure. Second, it would be beneficial if the whole process is controllable by means of additional constraints, for example, a specific substrate may lead to a particular nanoobject morphology. An impressive example of such a strategy is aryl halide C–C coupling on surfaces allowing for construction of various 1D and 2D structures. In particular, when aryl halide C–C coupling is combined with cyclodehydrogenation reaction it facilitates synthesis of miscellaneous graphene derivatives, such as nanoribbons of different widths and diverse edge topology.
关键词： On-Surface Polymerization,Semiconductor Surfaces,Aryl–Aryl Coupling,Ge(001):H Surface,Rutile Titania
更新于2025-09-10 09:29:36
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Reference Module in Chemistry, Molecular Sciences and Chemical Engineering || Synchrotron-based Spectroscopy In On-Surface Polymerization of Covalent Networks
摘要： Synchrotron radiation is a powerful tool to probe physical properties of materials on the nanoscopic scale. It can provide a chemical fingerprint of a nanomaterial with unrivalled resolution, it can measure the geometric structure down to thousands of a nanometer with not only elemental sensitivity but also chemical sensitivity, and it can study charge transfer dynamics in the sub-nanosecond regime. Within this article the application of synchrotron radiation to studying on-surface catalysis, to the view of forming two-dimensional covalent networks, will be explored.
关键词： covalent networks,on-surface polymerization,Normal Incidence X-ray Standing Waves,Synchrotron radiation,X-ray Photoemission Spectroscopy,Near Edge X-ray Absorption Fine Structure
更新于2025-09-10 09:29:36
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Rapid Self-healing Film From Novel Photo Polymerization Additive.
摘要： Self-healing materials have ability to repair damage by themselves. Their properties have been developed to increase the reliability of materials. Generally, self-healing polymers have been developed by thermal polymerization. Especially, hydrogel materials showed relatively rapid recovery and good-healing efficiency. However, it is very difficult to restore their properties without the self-healing mediator such as water. Herein, we report the novel type of self-healing polymer using photo-polymerization. This is achieved through an unprecedented concept of an additive of photopolymerization, named as ‘healer’ which can act as a physical crosslinker between main chains and a self-healing mediator in hydrogel materials. This transparent, easily fabricated self-healing polymer healed scratch in 40 seconds as well as restored the mechanical properties to 82%.
关键词： Self-healing properties,Supramolecular chemistry,Scratch recovery,Photo-polymerization,Polymers
更新于2025-09-10 09:29:36
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Ortho-substituted azobenzene: shedding light on new benefits
摘要： Novel functional polymeric microcapsules, based on modified azobenzene moieties, are exhaustively investigated, both from a theoretical and experimental points of view. Theoretical calculations and several measurements demonstrate that visible light can act as a trigger for release of encapsulated material, as a consequence of trans-cis isomerization which modifies microcapsule surface topography and can induce a “squeezing” release mechanism. Interfacial polymerization of an oil-in-water emulsion is performed and leads to core-shell microcapsules which are characterized by means of atomic force microscopy (AFM), optical microscopy (OM), scanning electron microscopy (SEM) and light scattering. These analyses put into evidence that microcapsules’ size and surface morphology are strongly affected by irradiation under visible light: moreover, these changes can be reverted by sample exposure to temperatures around 50?°C. This last evidence is also confirmed by NMR kinetic analyses on modified azobenzene moiety. Finally, it is shown that these smart microcapsules can be successfully used to get a controlled release of actives such as fragrancies, as a consequence of visible light irradiation, as confirmed by an olfactive panel.
关键词： microcapsules,interfacial polymerization,ortho-substituted azobenzene,Chemistry for Beauty and Health 2018
更新于2025-09-10 09:29:36